Hi. Thanks for your query. Noted the history, albeit short and specific and understood the concerns. Vomiting while travelling in a bus and car at the age of 23 indicates that you have something called as motion sickness . In motion sickness one looks outside and while watching the trees or any stationary objects but feels like they are moving but actually the bus is moving, they get nystagmus means continuous movement of the eyeballs from to to fro and thus the nausea and vomiting is occurring due to the stimulus reaching the vomiting center. Such things can occur even when you are sitting in merry-go-round or the large round wheel. This may be self-limiting as one s brain gets accustomed with the movements like these. You can certainly take tablets that stabilize such a phenomenon like Avomin half hour before the travel. Another is your mental determination dampening such a feeling. Take care, stop worrying as many people suffer from such things but eventually get okay.